Surgical product for dressing and treating wounds, and method of manufacture

ABSTRACT

An improved surgical fabric for covering and treating wounds and promoting healing thereof is described. The fabric includes nonsticking loops, sheared or unsheared, on at least one face for contacting the wound and for spacing the remainder of the fabric away from the wound. The yarn loops may be synthetic and may include a polyfluorinated polyolefin in filament, spun or plastic ribbon form as a nonsticking material, or may incorporate spun yarns of natural fibers suitably treated to impart nonstick characteristics. The nonsticking loops may be included as part of a knitted fabric construction, and additional, but shorter loops, sheared or unsheared, may be provided in the same fabric for wicking and/or absorbing liquids away from the region of the wound which is being treated. The improved surgical fabric may be produced on small circular knitting machines so as to produce a tubular, seamless fabric which can be placed around a limb or other body portion which is to be covered and treated. Stretch material may be incorporated in the tubular fabric to help prevent the accumulation of wound fluids and to assist in the retention of the dressing on a preferred placement over a wound. Although the fabric is described with reference to important surgical applications, it will be understood that the fabric is generally useful in applications requiring a transmittal and/or absorption of liquid from any surface area, as for example in diaper constructions or constructions for other articles of apparel.

nite States Patent Victor ,1. Lombardi 2715 Charlotte Lane, Burlington.NC

[72] Inventor [45] Patented [54] SURGICAL PRODUCT FOR DRESSING ANDTREATING WOUNDS, AND METHOD OF MANUFACTURE 43 Claims, 10 Drawing Figs.

[52] U.S.Cl 128/156, 128/284, 66/194 [51] lnt.C1 A611 15/00 [50] Fieldof Search 128/155- 56] References Cited UNITED STATES PATENTS 2,764,97610/1956 Skiles et a1 128/156 2,943,623 7/1960 Thompson... 128/155UX3,040,551 6/1962 Urlaub 128/284UX 3,085,309 4/1963 Olson 128/284UX3,113,570 12/1963 l-lolliday et a1 128/284 3,367,333 2/1968 Scheier128/284 3,441,021 4/1969 Endres 128/ 156 FOREIGN PATENTS 744,572 2/1956Great Britain 128/156 14 y \l 4 l4 Primary Examiner--L. W. TrappAttorney (ushman, Darby & Cushman ABSTRACT: An improved surgical fabricfor covering and treating wounds and promoting healing thereof isdescribed. The fabric includes nonsticking loops, sheared or unsheared,on at least one face for contacting the wound and for spacing theremainder of the fabric away from the wound. The yarn loops may besynthetic and may include a polyfluorinated polyolefin in filament, spunor plastic ribbon form as a nonsticking material, or may-incorporatespun yarns of natural fibers suitably treated to impart nonstickcharacteristics. The nonsticking loops may be included as part of aknitted fabric construction. and additional, but shorter loops, shearedor unsheared, may be provided in the same fabric for wicking and/orabsorbing liquids away from the region of the wound which is beingtreated. The improved surgical fabric may be produced on small circularknitting machines so as to produce a tubular, seamless fabric which canbe placed around a limb or other body portion which is to be covered andtreated. Stretch material may be incorporated in the tubular fabric tohelp prevent the accumulation of wound fluids and to assist in theretention of the dressing on a preferred placement over a wound.Although the fabric is described with reference to important surgicalapplications, it will be understood that the fabric is generally usefulin applications requiring a transmittal and/or absorption of liquid fromany surface area, as for example in diaper constructions orconstructions for other articles of apparel.

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f PATENIEH FEB 9m y I 356L441 sum m4 'IMIM SURGICAL PRODUCT FOR DRESSINGAND TREATING WOUNDS, AND METHOD OF MANUFACTURE BACKGROUND AND BRIEFSUMMARY OF THE INVENTION This invention relates to fabrics of loopconstruction, sheared or unsheared, for surgical applications, and moreparticularly, the invention is concerned with providing an improvedsurgical dressing or bandage, which includes nonsticking components forpromoting drainage, ventilation, and healing of a wound relative to themain body of the fabric which is dressing and covering the wound.

In the treatment of wounds, certain significant factors must beconsidered in order to assure quick healing of a wound without danger ofinfection. These factors include provisions for proper drainage of thewound secretions, ventilation of the wound to prevent overheating,nonadhesion of the wound to a dressing which is covering it, andimmobilization of the wound during the healing process.

Effective drainage hastens the drying of a wound and promotes fasterhealing and resistance to infection. It is known that this factor isespecially important during the first few days of a healing process,when the danger of infection is greatest. Accordingly, it has been apractice to apply dressings to wounds for assisting in the absorptionand removal of secretions from the wounds. Furthermore, clinical testshave demonstrated that compression of a wound by a highly absorbentmaterial helps to prevent the accumulation of wound fluids, therebyaccelerating the healing process while minimizing exposure to infection.However, the compression of a highly absorbent material on a wound mayresult in an adhesion of wound tissue to the dressing material, and thistends to retard the healing process because the new tissue or scabassociated with the wound may be partially or completely torn off whensuch a dressing material is changed. As a result, there is a tendency tochange dressings less frequently than would normally be desirable, andthis practice can result in inadequate ventilation and overheating of awound, thus increasing susceptibility to infection. It is also importantthat a wound be immobilized as much as possible to insure healingwithout disturbance by external pressures. Such pressures frequentlyarise from shrinkage of the bandage or dressing material which iscovering the area of the wound, and this may result in pain andirritation of the wound and a prolonging of the healing process.

Various attempts have been made in the past to improve bandages,dressings and other surgical fabrics or products which can be utilizedfor covering and protecting a wound which is being treated and healed.Some prior art attempts have emphasized the importance of immobilizationof a wound by maintaining shrinkable threads of a dressing out ofcontact with a wound. Such an arrangement is shown in US. Pat. No.2,924,252, Feb. 9, I960. Also, a certain amount of breathing" orventilation for a'wound has been attempted by adding a foam rubber layerto a bandage or dressing, as exemplified in patent 3,033,201, May 8,1962. Also, it is known to include hydrophobic and hydrophilic fibers ina woven fabric which is intended to be used as a diaper as disclosed in3,1 13,570, Dec. 10, 1963. However, the present invention is directed toa substantial improvement in a surgical fabric which may be used fordressing wounds and which considers all of the factors discussed abovewith respect to a quick healing of a wound without danger of infection.

The surgical product of this invention is constructed to satisfy therequirements of drainage, nonadhesion, ventilation and immobilization ofa wound, as discussed above. These factors are satisfied by theprovision of novel loop constructions, sheared or unsheared, for thefabrics of this invention, which may be produced on weaving, tufting,stitch or loop bonding, flocking, and on warp as well as weft knittingequipment. The surgical fabrics which will be described in detail belowmay comprise a single-face loop construction wherein loops appear on oneside of the fabric only, or the fabrics may be of doubleface loopconstruction having loops on both sides of the fabric. It is alsointended that the improved fabrics of this invention may be produced asopen width or as tubular constructions. Furthermore, it is contemplatedthat the loop constructions of this invention may be sheared on anoverall or a random basis to create pile effects in the fabric. In thisregard, shearing will expose more of the filaments or fibers of the loopyarns thereby facilitating the wicking and/or absorbing of wound fluidsand at the same time enhancing the nonsticking characteristics of theconstruction. In addition, whether in continuous loop form or in shearedform, the fabrics of this invention may incorporate in the loop yarns.fibers. slit plastic ribbons, or filaments of dissimilar shrinkcharacteristics. This will permit, in desired instances, during theprocess of manufacture, the formation of loops of one level throughoutthe fabric construction, and then by the appropriate application of heatduring the finishing process, the shrinkage of certain of the loops morethan others, thereby creating the different levels in the finishedfabric for the purposes herein described.

The products may be knitted on circular knitting machines of smalldiameter to produce seamless, tubular loop constructions which areespecially suitable for use on leg and arm wounds. In addition, thetubular knit constructions can incorporate stretch yarn components,which may be in the'form of compressive bands located at opposite endsof the tubular dressing product. The spaced bands function to applysufficient constrictive force to help prevent the accumulation of woundfluids, while at the same time obviating the need for adhesive tapes orother means for holding the surgical dressing in place. 1

The improved surgical product of this invention may be in the form of afabric, whether knitted or not knitted, having a loop construction,sheared or unsheared, in at least one face of the fabric. The loopand/or pile construction may be single or multiple level, and the saidmultiple level may be created mechanically or by the use of loop yarnswhich shrink in differential amounts in the presence of heat.Furthermore, by the provision of a loop and/or pile construction, airpockets are incorporated in the structure and these assure adequateventilation and drainage of a wound covered by' the surgical dressing ofthis invention. Further, the loop or pile construction of this inventionincludes a nonsticking characteristic for all loops or pile whichnormally contact the wound, and such a characteristic is achieved byfon'ning the wound contacting loops or pile from a material which mayinclude a polyfluorinated polyolefin to impart nonstickingcharacteristics. It has been found that such loops may in someinstances, be made with a monofilament yarn formed from a copolymer oftetrafluorethylene and hexafluoropropylene (FEP), with a multifilamentyarn formed from a homopolymer of tetrafluorethylene (TFE), or with yarnspun with fibers of the above polymers. In addition, it has been foundthat such loops may be made with ribbons slit to appropriate widths fromfilms produced with resins of the above polymers (sold under theRegistered Trademark "Teflon"). It will be understood that spun yarns ofnatural fibers may be treated with resins of the polymers noted above toimpart the nonsticking characteristic.

The invention also provides for multiple level loop constructionswherein longer loops are made with yarn or slit film in narrow ribbonform having a nonsticking characteristic, while lower level loops aremade from a yarn which has wicking or absorbing characteristics. Whenthe multilevel loop construction appears on one face only of the fabric,it is preferred that the longer loops be made from a ployfluorinatedpolyolefin yarn or slit ribbon and that the shorter loops be made from ahighly absorbent yarn such as cotton. However, if this constructionincludes a so-called backing or ground yarn, then the longer loops canbe made with the polyfluorinated polyolefin yarn, the shorter loops witha yarn exhibiting good wicking characteristics, and the ground yarn witha highly absorbent fiber such as cotton. On the other hand, when thedressingproduct is of the type having a double-face loop construction,it is preferred that a multilevel loop construction be provided on thewound contacting face while a single level, highly absorbent loopconstruction is provided on the opposite face of the dressing. Themultilevel loop construction preferably includes long loops which have anonsticking characteristic and shorter loops having a wickingcharacteristic for transmitting liquid to the highly absorbent loops onthe opposite face of the dressing.

The invention further contemplates a construction in which differentialloop levels are achieved by incorporating in the fabric loop yarnsexhibiting shrinkage characteristics different from each other. Forexample, if a construction of single loop level is provided with apolyfluorinated polyolefin yarn or slit film such as Teflon at certainloops, and a shrink yarn such as polyvinyl chloride or polyvinylidenechloride (such as the polyvinyl chloride fiber sold under the RegisteredTrademark Rhovyl" by Societe Rhovyl) at certain other loops, and acotton yarn for the backing or ground, and the construction subjected tosuitable heat during the finishing process, the loops in which thepolyvinyl chloride is present will contract thereby bringing their levelbelow that at which the Teflon loops remain. Consequently, the Teflon"loops which contact the wound will prevent sticking of the dressing tothe wound, whereas the shrink yarn such as Rhovyl," which also exhibitsexcellent wicking characteristics, will convey the wound secretions tothe absorbent backing or ground cotton yarn. Furthermore, ribbons slitto an appropriate width from a polyolefin film such as heatshrinkablcpolyethylene may be used to provide the shrinking characteristicpreviously noted.

It will be appreciated that if the previously described loop fabric issheared on an overall basis as one of the steps of its manufacture priorto exposing it to suitable heat, differential shrinkage of the shearedloops will create a multiple level pile fabric. This pile constructionwill expose more ends of fiber at an upper level to provide gentlercontact between the bandage and the wound, and more ends of fiber at alower level away from the wound to provide increased capacity foraccelerating the wicking of wound fluids to an outer absorbent fiber.Furthennore, it will be understood that if the so-called higher loopsincorporate the shrink yarn, such as polyvinylidene chloride, the lowerloops, the nonstick polyfluorinated polyolefin component, and theground, the absorbent cotton yarn, and the fabric sheared to a levelslightly above that of the polyfluorinated polyolefin loops, randomsheared effects can be developed. By subjecting such a random shearedconstruction to suitable heat, the polyvinylidene chloride pile can beshrunk to a level below that of the unsheared polyfluorinated polyolefinloops.

The invention also provides for multiple-level loop constructionscomprising yarns, described previously, in which the loops arepositioned closer to the so-called ground fabric. This construction maytake the form of a float configuration in which longer floats maycontain the nonstick yarn, the shorter floats, the wicking yarn, and theground fabric, the absorbent cotton yarn. This construction will resultin a flatter, lighter weight surgical dressing uniquely suited for thetreatment of less serious wounds.

As already mentioned, a knitted product may be formed on a smalldiameter circular knitting machine to provide a tubular, seamlessdressing product having all of the desired loop constructions. Thetubular dressing product has special utility for covering limbs of thebody, and a stretch yarn component may be incorporated in such a productto provide for a compression of the tubular dressing around the woundarea. In a preferred tubular dressing product, loop constructions willbe provided only in the area of the dressing which is intended forcovering a wound, and the remainder of the dressing may be fonned withno loops so as to decrease the weight of the dressing product. In thispreferred construction, stretch bands may be provided at each end of thetubular dressing so as to compress the dressing at spaced regionsadjacent to the wound area. In this manner, a wound may be easilycovered and protected, and the dressing is maintained in its requiredposition without the use of adhesive tape or other securing means.

BRIEF DESCRIPTION OF DRAWINGS FIG. I is a sectional clevational view ofa surgical dressing fabric of this invention wherein the fabric isprovided with a multilevel loop construction on a single face thereof;

FIG. 2 is a view similar to the view shown'in FIG. I, but showing asurgical dressing fabric having loop constructions on opposite faces ofthe fabric;

FIG. 3 schematically illustrates patterns of loop construction which maybe utilized in surgical fabrics according to this invention;

FIG. 4 illustrates a further pattern of loop construction which may beused in a surgicalfabric;

FIG. 5 is a stitch diagram of a knitted fabric made in accordance withthis invention and having the loop construction pattern shown in FIG.3A;

FIG. 6 illustrates a tubular knitted fabric incorporating loopconstruction and other features of this invention;

FIG. 7 is a sectional, elevation view of a surgical dressing fabric ofthis invention wherein the fabric is provided with a single-level loopconstruction on a single face which has been sheared as one step in itsmanufacture;

FIG. 8 is a view similar to FIG. 7 illustrating the multiple levels ofpile resulting from the differential shrinkage of the sheared loopyarns;

FIG. 9 is a perspective view illustrating a multiple level loopconstruction in which the loops are positioned closer to the groundfabric; and

FIG. 10 is a stitch diagram of a knitted fabric made in accordance withthis invention and having the loop construction pattern shown in FIG. 9.

DETAILED DISCUSSION OF THE INVENTION Referring to FIG. I, a surgicalfabric made in accordance with this invention and suitable for dressinga wound is indicated generally at 10. The fabric may be of a knitted ornonknitted construction, but an important feature of the invention isthe provision of a loop construction on at least one face of thesurgical fabric so that the main body of the fabric is spaced away fromactual contact with a wound area 12. In the FIG. I embodiment, amultilevel loop construction is shown on a single face of the fabric,that face being the surface which normally contacts and covers a woundto be treated. The multilevel loop construction includes relatively longloops [4 which actually contact the wound area 12 together with shorterloops [6 which are disposed away from a tight contact with the woundarea. The longer loops 14 function to space the main body of the fabricaway from the wound area for a sufficient distance to provide gooddrainage and ventilation of the wound. As discussed above, it isimportant to provide for removal of wound secretions away from the woundarea, and at the same time for ventilation of the wound to preventoverheating and susceptibility to infection. It is also a feature ofthis invention that the longer loops 14 function to prevent sticking oradhering of the surgical dressing to the wound itself. The long loops 14are preferably made from a yarn or slit film in narrow ribbon formhaving a nonsticking characteristic, and such a yarn or ribbon may bemade wholly or partially from a polyfluorinated polyolefin. The desiredcharacteristic of nonsticking is included in yarns, fibers, or filmsmade from polymers of tetrafluoroethylene (sold under the registeredtrademark Teflon), or polymers of trifluorochloroethylene (sold underthe registered trademark Kel-F). The feature of nonsticking is extremelyimportant for a rapid and safe healing of a wound, and this featurecoupled with provisions for adequate drainage and ventilation results ina substantially improved surgical product for covering, treating andprotecting wounds. By utilizing longer nonsticking loops 14 for actualcontact with a wound area, there is provided a good immobilization ofthe wound despite any minor shrinking or other movement of the surgicaldressing I0 relative to the wound. Since the contacting loops [4 are ofa nonsticking characteristic, shrinking movements or other movements ofthe bandage or dressing will not irritate or abrade the wound or anytissue which is healing in the wound.

The shorter loops I6 of the FIG. 1 embodiment may be made of a yarn suchas cotton or rayon yarns or fibers which is highly absorbent to liquids.The combination of a spacing layer of loops 14 with an absorbent layerof loops I6 provides for rapid drainage and ventilation of the woundarea in a manner which promotes healing. In an alternative arrangement,the shorter loops 16 may be made from a yarn having good wickingcharacteristics, such as a yarn including a polyvinyl chloride or nylon.Inthe alternative arrangement, a ground yarn I8 may be provided in thefabric to absorb liquid which is wicked away from the wound area by theshorter loops I6. Of course, it is to be understood that the ground yarn18 may be provided in a woven 'or nonwoven mat or fabric through whichloops l4 and 16 are formed. On the other hand, the entire surgicaldressing may be formed by knitting and the ground yarn 18 may beincluded in ground loops which combine the yarns of all of the loops.Furthermore, it will be understood that the surgical dressing of FIG. 1may include a wicking yarn for the ground yarn 18. With thisarrangement, a secondary covering material 19, exhibiting highlyabsorbent characteristics, may cooperate with the primary surgicaldressing to absorb the wound fluids which wick through the primarydressing. Consequently, the primary dressing will remain relatively freefrom wound secretions and the secondary covering material 19 can bereadily discarded as conditions dictate. Properly sterilized byautoclaving or otherwise, the primary dressing can be made reuseable.

FIG. 2 represents a second embodiment wherein a loop construction isprovided on opposite faces of a surgical dressing product 10. Asdiscussed for FIG. I, the wound contacting face may include a multilevelloop construction wherein longer loops l4 and shorter loops 16 aredirected toward the wound area when the dressing is applied. The longerloops 14 have a nonsticking characteristic while the shorter loops 16may have a wicking characteristic for carrying liquid away from thewound area. With the construction shown in FIG. 2, an increasedabsorption capacity can be provided by the loop construction 20 on aface of the dressing which is away from the wound area being covered.The loops 20 are preferably made from a yarn having a high absorptioncharacteristic so that wound secretions which are wicked toward theouter surface of the surgical dressing 10 can be absorbed and retainedby the dressing. It will be appreciated that the construction shown inFIG. 2 provides for a very substantial absorption surface, and yet,ample ventilation and drainage is provided in the region of the wounditself. Alternatively, the shorter loops I6 may also have a liquidabsorbing characteristic, and in that case, a dressing is provided witha maximum absorption capacity.

As shown schematically in FIG. 3, the high and low loop configurationswhich have been discussed with reference to FIGS. 1 and 2 may be of anydesirable pattern. For example, FIG. 3A illustrates a loop patternwherein high and low loop areas and areas having no loops at all arearranged in horizontally disposed rows. FIG. 38 illustrates a verticallypatterned configuration of high and low loops only. FIG. 3C illustratesa configuration wherein high and low loops are offset from one anotherin a more randomized pattern than that shown in B and C. Although thepatterns of FIG. 3 are shown for only one surface of a surgicaldressing, it will be understood that loop constructions and looppatterns may appear on a reverse side of the fabric as well. FIG. 4illustrates a further pattern example wherein concentric bands of highloops l4 and low loops 16 are provided on a surface of the surgicalfabric. Of course, any other pattern or configuration may be provided toaccommodate specialized dressing applications and wound treatments.

FIG. 5 illustrates a stitch diagram of a knitted fabric whichincorporates the loop construction features of the present invention.The stitch construction shown in FIG. 5 corresponds to the patternlayout schematically illustrated in FIG. 3A, and the numbered courses inFIG. 5 correspond to course numbers indicated in FIG. 3. The fabric ofFIG. 5 includes high loops 14 in course 1, low loops 16 in course 3, andcommon ground loops 22. As discussed with reference to FIGS. 1 and 2,the high loops 14 are preferably made of a polytetrafluorethylcne yarn,in filament. fiber of slit film form so that these wound contactingloops will have a nonsticking characteristic. The lower loops 16 may bemade of an absorbent yarn or a wicking yarn. The ground loops 22,similarly, may be made of an absorbent or a wicking yarn for thepurposes previously described. The yarn used to form ground loops 22 isinterknitted with the high loops 14 in course I, with the low loops 16in course 3, and knitted alone in courses 2 and 4.

FIG. 6 illustrates a novel surgical dressing product in the form of aseamless tubular dressing which may be knitted on a small diametercircular knitting machine. A conventional knitting machine may beadapted to form the high and low loop configurations of this inventionin the tubular article of FIG. 6, and the article may be formed withloops on one or both faces of the tubular product. When the multilevelloops are to be used on one face, such loops would normally appear onthe inner surface 24 of the seamless tubular product illustrated.Additionally, loops may be provided on the outer surface 26 forabsorbing liquid which is carried away from the wound area. The tubulararticle of FIG. 6 is especially useful for covering wounds on legs orarms, since it is only necessary to slide the tubular dressing over thelimb which is being protected until the area of the wound is covered. Itis also a feature of the FIG. 6 embodiment that a stretch component, orstretch yarn, may be included in the knitted structure of the tubulardressing. By giving the dressing a certain amount of stretch, adesirable compression of the wound area is provided for helping toprevent the accumulation of wound secretions. Although the stretch yarnor stretch component of the knitted article of FIG. 6 may be includedthroughout the knitted structure, it is preferred that stretch yarns belimited to bands 28 which are formed around the entire tubular structureand at spaced positions at opposite portions thereof. The bands 28 maybe so spaced as to lie adjacent opposite ends of a wound which is beingcovered, and thus, the constrictive forces of the tubular dressing willbe limited to the areas of the two bands 28. With this arrangement, thetubular dressing can be applied and held in place without a requirementfor adhesive tape or other securing means.

FIG. 6 also illustrates a preferred knitted construction wherein theloop construction is limited to the region of the tubular article whichis intended to cover the wound. This region is indicated generally at 30in the construction shown for FIG. 6, and the remainder of the body 32of the tubular dressing may comprise plain knitting so as to decreasethe fabric weight in those portions of the bandage or dressing whereadditional bulk is not required.

FIG. 7 illustrates a construction of this invention in which the loopshave been sheared to a single level, thereby exposing more of the endfibers or filaments. In this embodiment, there is shown the loop legs 14which result when the nonsticking loops have been sheared, and the looplegs 16 which result when the wicking loops have been sheared. Throughthe shearing process, a more gentle contact between the wound 12 and thenonstick yarn I4 is achieved, and at the same time,

improved wicking of wound fluids to the absorbent ground 18 is madepossible.

FIG. 8 represents a sheared fabric construction similar to that shown inFIG. 7. However, in this embodiment, the wicking yarn 16 also has thecapability for shrinkage which can be developed in the presence of heatduring finishing process. In this regard, a polyvinylidene chloride orpolyvinyl chloride yarn such as Rhovyl may be used to provide thedesired shrinkage and at the same time, the wicking required. It,accordingly, will be appreciated that differential loop or pile levelscan be achieved in a'construction which is of uniform loop or pileheight prior to exposure to heat. For example, if a fabric incorporatinga polyvinyl chloride fiber, such as Rhovyl 55 is subjected to a heatranging from l70 F. to 212 F., shrinkage of the polyvinyl chloridecomponent will result, and at 212 F. the shrinkage will approachapproximately 55 percent. Lesser shrinkage can be provided for by theuse ofother polyvinyl chloride fibers.

FIG. 9 is a further embodiment of the invention illustrating amultiple-level loop construction comprising longer nonsticking loops orfloats l4, shorter wicking loops or floats 16, and a ground fabricincorporating highly absorbent ground yarn 18. In this instance,however, both the nonsticking as well as the wicking loops arepositioned closer to the ground fabric resulting in a flatter as well asa lighter surgical dressing. A dressing of this character can beeffectively utilized for the less serious type of wound treatment. Inaddition to the use of long nonsticking loops 14 in combination with theshorter wicking loops [6 to create multiple'level loops, it will beunderstood that differential loop levels can also be created by the useof a fine count or light yarn for the wicking yarn, and a coarse countor heavier yarn for the nonsticking yarn. The heavier nonsticking yarnwill contact the wound whereas the light wicking yarn will function totransmit the wound fluids to the outer absorbent ground fabric. Ofcourse, the shorter loops 16 might include a fiber incorporating ashrinkage characteristic, alone or in combination with a wickingcharacteristic. as previously described. The use of a shorter loop 16,of FIG. 9, with a shrink characteristic will, upon the application ofsuitable heat to the fabric, cause the loop 16 to contract, therebydrawing the fabric in widthwise, and in so doing, forcing the loops l4outwardly to create differential levels between the loops 16 and theloops 14.

FIG. 10 illustrates a knitted stitch diagram of the construction shownin FIG. 9. The construction is referred to in the art as single jerseyhaving been produced on a knitting machine with a single set of needles.In the diagram, the ground fabric incorporates ground loops 23 made witha ground yarn l8, and the longer nonsticking loops 14 and the wickingloops 16 are introduced in the fabric as long and short lay-in loopsrespectively. It is to be understood that the long nonsticking loops andthe shorter wicking loops can be positioned in any desirableconfiguration in the fabric. It will be further appreciatcd that theconcept illustrated in FIG. 10 is equally applicable to fabrics of ribas well as other knitted constructions. When utilized in a fabric of ribconstruction, the surgical dressing may have the added advantage of notcurling at its edges.

Similarly, the use of heavy nonsticking yarns at certain warp andfilling positions of a woven fabric, and lighter wicking and/orabsorbent yarns at certain other positions in the same fabric, willresult in a flat lightweight woven construction exhibiting thenonsticking, wicking and/or absorbing characteristics desirable in asurgical dressing. In addition, a shrinkable fiber may be included in awoven fabric in the manner discussed for the knitted fabric of FIG. 9.

Having described the preferred embodiments of the present invention, itcan be appreciated that there is provided a substantially improvedsurgical dressing having a novel combination of features which promoteshealing of a wound. It is contemplated that many variations can be madein the invention, as described above, and the surgical dressing may bemade in any sizes or shapes that may be desired. For example, thetubular construction which was described with reference to FIG. 6 may beconceivably knitted in relatively long lengths with multilevel loopconstruction throughout the interior surface of the long tubular length.Such long lengths could then be cut or otherwise divided up intosuitable shorter sizes for adaptation to varying sizes of wounds. Theseand other variations and applications will become obvious to thoseskilled in the art, and all such variations and uses are intended to beincluded within the scope of the claims.

lclaim:

1. An improved surgical product suitable for dressing and treatingwounds comprising:

a knitted fabric having loops included in at least one face thereof,said loops being included in the knitting of the fabric, and said loopshaving a nonsticking characteristic and being of a sufficient dimensionto space the remainder of the fabric away from the wound so that thereis adequate ventilation and drainage of the wound with substantially nosticking of the fabric to the wound.

2. The surgical product of claim 1 wherein said loops include asynthetic yarn having a nonsticking characteristic.

3. The surgical product of claim 2 wherein said synthetic yarn includesa copolymer of tetrafluoroethylene and hexafluoropropylene to impartnonsticking characteristics.

4. The surgical product of claim 1 wherein said loops include a filmslit in narrow ribbon form and having a nonsticking characterisitc.

5. The surgical product of claim 4 wherein said film slit in narrowribbon form includes a homopolymer of tetrafluoroethylene to impartnonsticking characteristics.

6. The surgical product of claim 1 wherein said loops in clude a yarnspun with natural fiber and treated for nonsticking characteristics.

7. The surgical product of claim 2 wherein said synthetic yarn includesa homopolymer of tetrafluoroethylene to impart nonstickingcharacteristics.

8. The surgical product of claim 4 wherein said film slit in narrowribbon form includes a copolymer of tetrafluoroethylene andhexafluoropropylene to impart nonsticking characteristics.

9. The surgical product of claim 1 wherein said loops include apolyfluorinated polyolefin as a nonsticking material.

10. The surgical product of claim I and including additional loops insaid fabric which are of a smaller loop dimension than said loops,whereby said additional loops are normally spaced out of tight contactwith a wound when the surgical product is applied thereto.

11. The surgical product ofclaim 10 wherein said additional loops have ashrinking characteristic.

12. The surgical product of claim 11 wherein said additional loopsinclude a polyvinyl chloride as a shrinking material.

13. The surgical product of claim 11 wherein said additional loopsinclude a polyolefin film slit in narrow ribbon form as a shrinkingmaterial.

14. The surgical product of claim 1 wherein said fabric includes astretch component in its construction.

15. The surgical product of claim 1 wherein said product is formed andused as a tubular knitted product having no seams.

16. An improved surgical product for dressing and treating woundscomprising:

a knitted fabric having multilevel loops formed in at least one face inthe knitting thereof, said multilevel loops including longer loopsformed from a yarn having a nonsticking characteristic and shorter loopsformed from a yarn having a wicking or absorption characteristic, saidsaid longer loops being of a sufficient size and number to space saidshorter loops out of tight contact with a wound to be covered, wherebyadequate ventilation and drainage of the wound is assured, and whereinsubstantially no sticking or abrading of the wound by the surgicalproduct takes place.

17. An improved surgical product for dressing and treating woundscomprising:

a knitted fabric having multilevel loops formed in at least one face inthe knitting thereof, said multilevel loops including longer loopsformed from a film slit into narrow ribbons having a nonstickingcharacteristic and shorter loops formed from a yarn having a wicking orabsorption characteristic, said longer loops being of a sufficient sizeand number to space said shorter loops out of tight contact with a woundto be covered, whereby adequate ventilation and drainage of the wound isassured, and wherein substantially no sticking or abrading of the woundby the surgical product takes place.

18. The surgical product of claim 16 wherein said multilevel loops areformed and extend substantially vertically of the ground fabric.

19. The surgical product of claim 16 wherein said multilevel loopsextend substantially horizontally and are formed close to the groundfabric.

20. The surgical product of claim 19 wherein said multilevel loops areformed randomly in a knitted fabric.

21. The surgical product of claim 19 wherein said multilevel loops areformed as a lay-in in a knitted fabric at selected wale and coursepositions.

22. The surgical product of claim l6wherein said multilevel loops areformed with yarns of different size at each level.

23. The surgical product of claim 1 in combination with a separablesecondary material for absorbing wound fluids.

24. The surgical product of claim 16 wherein said longer loops include apolyfluorinated polyoletin as a nonsticking material.

25. The surgical product of claim 16 wherein said shorter loops includea polyvinyl chloride as a wicking material.

26. The surgical product of claim 16 wherein loops are formed on twoopposite faces of the fabric.

27. The surgical product of claim 16 wherein multilevel loops are formedon one face of said fabric and additional loops are formed on a secondface of the fabric.

28. The surgical product of claim 27 wherein said multilevel loops onthe one face include longer loops having a nonsticking characteristicand shorter loops having a wicking characteristic, and said additionalloops on the second face of the fabric being formed from a yarn havingan absorption characteristic, whereby liquid matter from the wound iscarried through the fabric when said one face of the fabric is I placedon the wound.

29. The surgical product of claim 16 wherein said fabric is a knittedfabric.

30. The surgical product of claim 16 wherein said fabric and all loopsformed therein are knitted on a circular knitting machine so as toproduce a seamless, tubular product.

31. The surgical product of claim wherein said knitted product includesa stretch yarn in the fabric.

32. The surgical product of claim 30 wherein said knitted tubularproduct includes a band of stretch material in said fabric to fix theposition of said tubular product around a limb or body portion having awound which is to be dressed and treated.

33. The surgical product of claim 32 wherein two or more bands ofstretch material are incorporated in said tubular product so as toprovide compression of said surgical product on opposite sides of awound being covered by the product.

34. The surgical product of claim 30 wherein said tubular knittedproduct includes an area of looped knitting in the portion of theproduct which is to cover a wound, and plain knitting in areas which arenot intended to cover a wound.

35; An improved surgical product for dressing and treating woundscomprising a knitted fabric having loops formed in at least one face inthe knitting thereof, said loops being sheared to form a pile, saidsheared loops being located in at least a single level above the knittedfabric, certain of said sheared loops formed with a material having anonsticking characteristic, and other of said sheared loops formed witha material having a wicking characteristic so that there is adequatevcntilation and drainage of the wound with substantially no sticking ofthe fabric to the wound.

36. The surgical product of 'claim 35 wherein the said sheared loopsformed with a material having the wicking characteristic also have ashrinking characteristic so that when they are shrunk they contract to alevel which is lower than the sheared loops having the nonstickingcharacteristic.

37. The surgical product of claim 36 wherein the said loops at a higherlevel are randomly sheared.

38. An improved surgical product suitable for dressing and treatingwounds comprising a knitted ground fabric incorporating a yarn having awicking or absorbing characteristic. and loops knitted integrallytherewith, said loops exhibiting nonsticking and wickingcharacteristics.

39. The surgical product of claim 38 wherein the ground fabricincorporates a yam having an absorbing characteristic.

40. The surgical product of claim 38 in combination with a secondarymaterial for absorbing wound fluids.

41. in a method for forming an improved surgical fabric having at leasttwo levels of loops, with a higher level of loops having a nonstickingcharacteristic and with a lower level of loops having a wickingcharacteristic, the improvement comprising the steps of:

knitting a looped fabric from at least two different yarns, andutilizing a shrinkable yarn in the fabric as a yarn for forming loopshaving a wicking characteristic, and

treating the fabric to shrink the shrinkable yarn, thereby providing afabric having wicking loops at a lower level than nonsticking loops.

42. The method of claim 41 wherein said shrinkable yam includes apolyvinyl chloride material, and wherein said treating step comprises astep of heating the fabric sufficiently to shrink the shrinkable yarn.

43. The method of claim 41 and including a step of shearing all loops ofthe fabric prior to treating the fabric, whereby a fabric having atleast two levels of sheared loops will be formed.

2. The surgical product of claim 1 wherein said loops include asynthetic yarn having a nonsticking characteristic.
 3. The surgicalproduct of claim 2 wherein said synthetic yarn includes a copolymer oftetrafluoroethylene and hexafluoropropylene to impart nonstickingcharacteristics.
 4. The surgical product of claim 1 wherein said loopsinclude a film slit in narrow ribbon form and having a nonstickingcharacterisitc.
 5. The surgical product of claim 4 wherein said filmslit in narrow ribbon form includes a homopolymer of tetrafluoroethyleneto impart nonsticking characteristics.
 6. The surgical product of claim1 wherein said loops include a yarn spun with natural fiber and treatedfor nonsticking characteristics.
 7. The surgical product of claim 2wherein said synthetic yarn includes a homopolymer oftetrafluoroethylene to impart nonsticking characteristics.
 8. Thesurgical product of claim 4 wherein said film slit in narrow ribbon formincludes a copolymer of tetrafluoroethylene and hexafluoropropylene toimpart nonsticking characteristics.
 9. The surgical product of claim 1wherein said loops include a polyfluorinated polyolefin as a nonstickingmaterial.
 10. The surgical product of claim 1 and including additionalloops in said fabric which are of a smaller loop dimension than saidloops, whereby said additional loops are normally spaced out of tightcontact with a wound when the surgical product is applied thereto. 11.The surgical product of claim 10 wherein said additional loops have ashrinking characteristic.
 12. The surgical product of claim 11 whereinsaid additional loops include a polyvinyl chloride as a shrinkingmaterial.
 13. The surgical product of claim 11 wherein said additionalloops include a polyolefin film slit in narrow ribbon form as ashrinking material.
 14. The surgical product of claim 1 wherein saidfabric includes a stretch component in its construction.
 15. Thesurgical product of claim 1 wherein said product is formed and used as atubular knitted product having no seams.
 16. An improved surgicalproduct for dressing and treating wounds comprising: a knitted fabrichaving multilevel loops formed in at least one face in the knittingthereof, said multilevel loops including longer loops formed from a yarnhaving a nonsticking characteristic and shorter loops formed from a yarnhaving a wicking or absorption characteristic, said said longer loopsbeing of a sufficient size and number to space said shorter loops out oftight contact with a wound to be covered, whereby adequate ventilationand drainage of the wound is assured, and wherein substantially nosticking or abrading of the wound by the surgical product takes place.17. An improved surgical product for dressing and treating woundscomprising: a knitted fabric having multilevel loops formed in at leastone face in the knitting thereof, said multilevel loops including longerloops formed from a film slit into narrow ribbons having a nonstickingcharacteristic and shorter loops formed from a yarn having a wicking orabsorption characteristic, said longer loops being of a sufficient sizeand number to space said shorter loops out of tight contact with a woundto be covered, whereby adequate ventilation and drainage of the wound isassured, and wherein substantially no sticking or abrading of the woundby the surgical product takes place.
 18. The surgical product of claim16 wherein said Multilevel loops are formed and extend substantiallyvertically of the ground fabric.
 19. The surgical product of claim 16wherein said multilevel loops extend substantially horizontally and areformed close to the ground fabric.
 20. The surgical product of claim 19wherein said multilevel loops are formed randomly in a knitted fabric.21. The surgical product of claim 19 wherein said multilevel loops areformed as a lay-in in a knitted fabric at selected wale and coursepositions.
 22. The surgical product of claim 16 wherein said multilevelloops are formed with yarns of different size at each level.
 23. Thesurgical product of claim 1 in combination with a separable secondarymaterial for absorbing wound fluids.
 24. The surgical product of claim16 wherein said longer loops include a polyfluorinated polyolefin as anonsticking material.
 25. The surgical product of claim 16 wherein saidshorter loops include a polyvinyl chloride as a wicking material. 26.The surgical product of claim 16 wherein loops are formed on twoopposite faces of the fabric.
 27. The surgical product of claim 16wherein multilevel loops are formed on one face of said fabric andadditional loops are formed on a second face of the fabric.
 28. Thesurgical product of claim 27 wherein said multilevel loops on the oneface include longer loops having a nonsticking characteristic andshorter loops having a wicking characteristic, and said additional loopson the second face of the fabric being formed from a yarn having anabsorption characteristic, whereby liquid matter from the wound iscarried through the fabric when said one face of the fabric is placed onthe wound.
 29. The surgical product of claim 16 wherein said fabric is aknitted fabric.
 30. The surgical product of claim 16 wherein said fabricand all loops formed therein are knitted on a circular knitting machineso as to produce a seamless, tubular product.
 31. The surgical productof claim 30 wherein said knitted product includes a stretch yarn in thefabric.
 32. The surgical product of claim 30 wherein said knittedtubular product includes a band of stretch material in said fabric tofix the position of said tubular product around a limb or body portionhaving a wound which is to be dressed and treated.
 33. The surgicalproduct of claim 32 wherein two or more bands of stretch material areincorporated in said tubular product so as to provide compression ofsaid surgical product on opposite sides of a wound being covered by theproduct.
 34. The surgical product of claim 30 wherein said tubularknitted product includes an area of looped knitting in the portion ofthe product which is to cover a wound, and plain knitting in areas whichare not intended to cover a wound.
 35. An improved surgical product fordressing and treating wounds comprising a knitted fabric having loopsformed in at least one face in the knitting thereof, said loops beingsheared to form a pile, said sheared loops being located in at least asingle level above the knitted fabric, certain of said sheared loopsformed with a material having a nonsticking characteristic, and other ofsaid sheared loops formed with a material having a wickingcharacteristic so that there is adequate ventilation and drainage of thewound with substantially no sticking of the fabric to the wound.
 36. Thesurgical product of claim 35 wherein the said sheared loops formed witha material having the wicking characteristic also have a shrinkingcharacteristic so that when they are shrunk they contract to a levelwhich is lower than the sheared loops having the nonstickingcharacteristic.
 37. The surgical product of claim 36 wherein the saidloops at a higher level are randomly sheared.
 38. An improved surgicalproduct suitable for dressing and treating wounds comprising a knittedground fabric incorporating a yarn having a wicking or absorbingcharacteristic, and loops knitted integrally therewith, said loopsexhibiting nonsticking and wicking characteristics.
 39. The surgicalproduct of claim 38 wherein the ground fabric incorporates a yarn havingan absorbing characteristic.
 40. The surgical product of claim 38 incombination with a secondary material for absorbing wound fluids.
 41. Ina method for forming an improved surgical fabric having at least twolevels of loops, with a higher level of loops having a nonstickingcharacteristic and with a lower level of loops having a wickingcharacteristic, the improvement comprising the steps of: knitting alooped fabric from at least two different yarns, and utilizing ashrinkable yarn in the fabric as a yarn for forming loops having awicking characteristic, and treating the fabric to shrink the shrinkableyarn, thereby providing a fabric having wicking loops at a lower levelthan nonsticking loops.
 42. The method of claim 41 wherein saidshrinkable yarn includes a polyvinyl chloride material, and wherein saidtreating step comprises a step of heating the fabric sufficiently toshrink the shrinkable yarn.
 43. The method of claim 41 and including astep of shearing all loops of the fabric prior to treating the fabric,whereby a fabric having at least two levels of sheared loops will beformed.